1. Description of the Prior Art
Landsailing craft have been in existence for over a hundred years going back to the Conestoga wagon and the square-rigged sails of the early pioneers seeking new, inexpensive means, to travel west and reap the rewards of the new frontier. Early efforts were met with only limited success due to a lack of strong, light, structural material, inexperience with aerodynamic sail designs and technological knowhow resulting in craft content to go only downwind.
With improved technology, materials, and computer analysis of sail designs and airfoil shapes, the last decade has shown the most promise in the development of an efficient, all-around, sailing craft for land transportation. Man has often sought an easier and more relaxed means to travel, and at minimum expense. Such a craft fulfills these needs.
Lately, there is an upsurge in bicycle sales and in the number of patents employing a sail attached to bicycles to assist in road travel. The inherent disadvantage in bike sails is due to a basic physical law: A sail erected on a vehicle will undergo a tremendous heeling moment (tipping force) exerted through the center of pressure C.P. (or center of effort C.E.) proportional to the force of the wind. This heeling moment is compounded on bicycles due to the vehicles high center of gravity C.G., and generally high placement of the C.P. of the sail, resulting in a dangerous, unstable, and uncontrollable craft. Such two-wheeled vehicles are greatly limited in permissable sail area and are prone to tipping over in gusts. In U.S. Pat. No. 2,443,565, "Land Sail Vehicle," June 15, 1948, Land realizes a four-cornered frame of bicycle origin with more than one front wheel and using a drive shaft for the rear wheels. In U.S. Pat. No. 4,049,287, "Sail Vehicles," Sept. 20, 1977, Dudouyt's steering means will not adapt to the desired wide spacing of the wheels most directly below the C.P. of the sail to reduce heeling moment in this type of vehicle. In U.S. Pat. No. 3,572,740, "Collapsible Sail Propelled Vehicle," Mar. 30, 1971, Rypinski reveals a land sailing craft with some proven good features but unsuitable for road travels as it lacks an optional occupant propelling means if the wind should fail. As understood, such means could not be easily adapted without major redesign. Features in claim 1 elicit a chassis design utilizing: " . . . a pair of rear struts . . . a forward strut . . . a coupling means . . . " which are obviated and have no counterpart in the present invention.
In Popular Science, Nov. 1976, "Land Sailer for the Highway," Hybrid Windmobile, p. 102: James Amick realizes a three wheel electric drive windcar for highway use. The design is especially adapted to reduce drag to more effectively extend the range of the batteries. Amick's invention, although sleek in appearance, is not well suited to use the full power of the wind due to the effective small sail area comprised of rigid, symmetrical, airfoil sails. Experimentation and research have shown such sail configurations efficient only if the prevailing winds (true wind direction) approach the longitudinal axis of the vehicle from an angle of forty-five degrees or more. This disadvantage is compounded further by the lack of trimming control of the sail members preventing the vehicle from closehauling or developing thrust from a direction more directly into the prevailing winds. Also Amick's design is unduly heavy (720 lbs.), expensive (about $5,000), and complex, As understood the vehicle is not truly energy efficient since the batteries eventually require an external charge and there is no means for occupant propulsion.
Finally, a good example of the heretofore state of the art is illustrated in Popular Science, April 1980, pp. 106-108, "Landsailer for the 80's" by Paul Bolon and "a 25 mph prairie schooner", by Ben Kocivar (designed by Randy Schlitter). Bolon's landsailer would be unsuitable for road travel due to lack of occupant propelling means and a very limited steering means, inadequate for saftey in high speed congested travel on roadways. Schlitter's vehicle, although practical, has several deficiencies known to those skilled in the art. Said vehicle requires a "live" rear axle drive means activated by the pedals. Such axles are necessarily of solid steel construction and quite heavy. Also such axles provide no means for longitudinal adjustment to adapt to varying wind and road conditions. Additionally, experiment and research have shown a frame utilizing a bicycle-type front fork steering arrangement is not durable, stable, or reliable on a sailing vehicle due to the great side-loading wind forces which tend to lever and distort the fork construction. Furthermore, it is known in the art that excluding sail area, vehicle weight and rolling resistance determine the efficiency of a sailing craft. Wheels that include an integral transmission or ratchet means generally will not coast as freely as simplified, independent, ball bearing wheels of the same diameter as in the present invention.
In conclusion, Schlitter's vehicle places the lowest portion of the pilot's seat, at or above the hubs of the rear wheels. It is known in the art that the pilot of said vehicles constitutes the major portion of the vehicle's loaded weight and the position of said pilot will greatly infuence the handling characteristics of said craft. The present invention places the lower portion of the seat somewhat lower than the wheel hubs, advantageously, lowering the C.G. of said vehicle and correspondingly reducing the heeling moment permitting greater sail area, speed, and safety.